Induction hardening is becoming an affordable and cost-effective substitute for carburizing heat treatment. Research indicates an 85% decrease in heat treatment process steps when migrating from traditional gas carburization to DPIH.
This blog discusses how induction hardening cuts costs, processing times and environmental footprint without sacrificing high-quality hardening outcomes.
What is Carburizing?
Carburizing is a process of case hardening that is applied to enhance the surface hardness of low-carbon steels. The component is first heated in a carbon-rich environment, and the carbon atoms diffuse into the surface layer. The component is then quenched and tempered after this diffusion process to produce a hard surface layer with a tough but ductile interior. The process is normally applied to parts requiring deep case depths, such as gears, shafts and other highly stressed parts.
Carburizing is done on low-carbon steels (such as SCM415 and SCM420) because they have the capacity to take up carbon and develop a hardened case, hence suitable for components that need deep surface hardness.
Induction Hardening Process
Induction hardening process, on the other hand, employs electromagnetic induction to quicken the heating of the surface layer of medium- or high-carbon steel parts. Rapid quenching follows after localized heat treatment which hardens the surface layer to martensite but not the core. Induction hardening process does not utilize carbon diffusion like carburizing, so the process is much quicker.
Induction hardening is best suited for those pieces that need selective hardening like gear teeth, bearing surfaces or other parts that only certain areas need to be hardened. Process speed and accuracy lower energy usage and increase throughput.
Key Differences in Operations
| Factor | Carburizing | Induction Hardening |
| Processing Time | Several hours needed | Needs minutes or seconds |
| Energy Consumption | High, as furnace times are long | Low, only heats the surface layer |
| Batch vs. Single-Piece | Batch process | Individual part processing |
| Distortion | High, resulting in extra machining | Least distortion, no additional machining |
| Cost Effectiveness | More so through energy and time consumption | Less energy consumption, more cost-effective |
Material and Performance Factors
Carburizing is normally carried out on low-carbon steel, like SCM415 and SCM420, with excellent carbon absorption qualities. The component turns harder at the surface but remains ductile in the centre, which is important where components, including gears and shafts, need both toughness and resistance to wear.
Induction hardening, on the other hand, is done to medium- and high-carbon steels, for example, S45C, SCM435 and SCM440. These steels already possess the needed carbon to produce martensite when they are heated and quenched quickly. Induction hardening is used for parts that need selective hardening process of a particular area, like gear teeth, bearing races or pins, with precise control over the depth of hardening.
Hardness Profiles and Case Depth Control
| Process | Hardness Profile | Case Depth Control |
| Carburizing | Gradual hardness change from surface to core | Directed by furnace time and temperature |
| Induction Hardening | Sudden change, hard surface with softcore | Exact control through coil power and heating time |
Carburizing parts show a gradual variation in hardness from the surface to the centre, so these parts should be used where wear resistance and toughness are needed. Controlling the case depth in carburizing involves furnace time and temperature adjustments, which are energy-intensive and not as accurate.
Induction hardening presents a more controllable process. With the power of the coil and heating time, induction hardening provides accurate control of the hardened surface depth. This high-precision method minimizes energy waste and provides quality consistency.
Energy Consumption & Environmental Impact
- Carburizing: Involves heating entire parts for long periods of time, resulting in high energy use.
- Induction Hardening: Heats only the surface layer, minimizing energy consumption.
Carburizing’s lengthy furnace times are energy intensive. Furthermore, carburizing has carbon-rich emissions and specialized gas management or liquid carburizing bath control requirements. Induction hardening, on the other hand, is environmentally friendly, with low emissions and without the necessity for elaborate atmospheric control equipment.
Equipment and Maintenance
| Equipment Maintenance | Carburizing | Induction Hardening |
| Furnace Maintenance | More frequent, requires cleaning downtime | Less frequent, lower maintenance requirements |
| Environmental Control | Needs atmosphere control for carbon | Low environmental control requirements |
Carburizing furnaces are in constant need of maintenance, with atmosphere control and scheduled downtime for repair and cleaning. This incurs operating costs and decreases overall efficiency. Induction hardening equipment, however, demands less downtime and maintenance requirements tend to be lower, particularly in automated systems.
Conclusion
Induction hardening is a more efficient carburizing alternative. It provides quicker processing times, lower energy usage and is cost effective. Its accurate control over hardening process depth and capability to selectively harden certain areas makes it perfect for usage, such as gears and bearings.
While carburizing is still necessary for deep case depths and big batch production, induction hardening is a cost-effective option for today’s manufacturing environments looking for flexibility, accuracy and sustainability. Accurate Edge hardening steel offers induction hardening is a proven economical option.
Frequently Asked Questions
1. What is the difference between carburizing and induction hardening?
Carburizing involves heating low-carbon steel in a carbon-rich environment to harden the surface, whereas induction hardening uses electromagnetic induction to rapidly heat and harden specific areas of medium- or high-carbon steel without altering the core.
2. Why is induction hardening considered more cost-effective than carburizing?
Induction hardening is faster, consumes less energy, requires less maintenance, and reduces distortion—leading to less rework and lower operational costs compared to the lengthy, energy-intensive carburizing process.
3. What types of materials are suitable for induction hardening?
Induction hardening is ideal for medium- and high-carbon steels such as S45C, SCM435, and SCM440, which naturally contain sufficient carbon for hardening without requiring diffusion.
4. Can induction hardening achieve the same hardness as carburizing?
Yes, induction hardening can produce high surface hardness comparable to carburizing, with the added benefit of more precise control over the hardened depth and minimal distortion.
5. Is induction hardening environmentally friendly?
Yes, induction hardening is more environmentally friendly because it uses less energy, does not require controlled atmospheric gases, and generates lower emissions compared to carburizing.
